Urethane polymers are thermostable, durable, and can be manufactured with a very broad range of hardness. Many different reactants can be used to make urethane polymers. As such, urethane polymers can be used in a wide variety of applications. For example, urethane elastomers have particularly good impact absorption and wear resistance characteristics and can be manufactured to virtually any desired shape and flexibility, making them good candidates for many padding applications.
However, conventional urethanes contain toxic materials that would harm cells that are subjected to prolonged contact with the urethane. The other characteristics make elastomeric urethanes well suited for padding, for example in medical applications, such as in sleeves, splints and braces. The cytotoxicity of urethanes precludes their use in applications requiring direct contact with the skin without a protective layer to form a barrier against the cytotoxic effects of the urethane. The addition of a protective layer complicates the process of manufacturing articles such as sleeves, splints and braces. Using a protective layer also adds another component that can wear with time, and potentially provide a surface where dirt, microbes or other biological hazards, such as fungus and mold, can accumulate raising cleanliness issues.
For this reason, elastomeric silicone is currently the material of choice for skin contact applications where elastomeric properties are desirable. Silicone elastomers are flexible, durable and non-toxic, making them an ideal candidate for applications requiring human skin contact. However, silicone is costly and therefore very expensive to use in large quantities.
There is a long felt need to make a urethane elastomer which is non-cytotoxic and flexible such that it can be used in applications having contact with human skin, such as padding for sleeves, splints, braces and the like.